It is conventional in the color television field for the color video signal to be processed in encoded (e.g. NTSC) form. Although component signals (generally R, G, B) are produced in cameras and telecines, it has hitherto been usual to encode these component signals and carry out further operations on the encoded signal. Recently, however, the use of component signals (R, G, B or luminance, and two color difference components) has increased, with the result that the need for accurately identifying different characteristics (among them gain and delay) of the channels through which the component signals pass has arisen. It will be understood that unless the gain and delay of the channels are equal, when the components are encoded and the encoded signal is used by a television display, the picture produced by the encoded signal on the television display will not be an accurate representation of the original scene.
The need to provide for accurate measurement of the characteristics of the different channels of a component video system was discussed at International Broadcasting Conference which took place at Brighton, England in September, 1984. In the paper "Measurements in a Television Component Environment" by A. James and P. J. Marshall, mention is made of the use of a 500 kHz sine wave for measuring delay difference among the channels. This measurement is carried out by impressing a 500 kHz signal on the channels, two at a time, and observing on a dual trace oscilloscope whether the zero crossing points of the output sine waves are aligned. This type of measurement, however, is rather difficult to carry out, and, in any event, does not provide an accurate indication of gain difference.